【作者】 侯麟；

【导师】 邓仕槐；

【作者基本信息】 四川农业大学 ， 环境科学， 2010， 硕士

【摘要】 酸雨已成为目前全世界环境问题之一,也是我国的重要环境问题。酸雨危害引起的经济损失和对生态平衡及植物本身影响的严重性已越来越引起人们的关注。本文以长势良好且树龄相同的木兰科植物白兰花(Michelia alba.DC)为实验材料,采用盆栽方式,用模拟酸雨的处理方法,研究了白兰花在模拟酸雨胁迫下的形态指标、生长量指标和某些生理生化指标,探索了白兰花对酸雨胁迫的抗性机理,为酸控制区城市绿化植物的选择和酸雨理论研究提供依据和参考。研究结果表明：(1)酸雨对白兰花的伤害与酸雨的pH值密切相关,不同酸度酸雨对白兰花的伤害不同。酸雨的酸度越高,频次越多,对白兰花的伤害程度和抑制作用就越大。酸雨对白兰花的可见伤害阈值为pH 3.0；酸雨pH 2.0时,白兰花对酸雨污染敏感等级为Ⅱ。(2)白兰花新梢增长率和生长率均随着酸雨的pH值减小而逐渐降低,且各处理的新梢增长率和生长率分别都与pH 5.6(CK)呈显著性差异(p<0.05),白兰花的生长量指标对酸雨较为敏感。(3)酸雨胁迫明显影响白兰花的光合作用。与白兰花光合作用相关的叶绿素含量、叶绿素a/b值、净光合速率、气孔导度、胞间CO2浓度、蒸腾速率随着酸雨pH值的减小而下降,引起白兰花光合作用能力下降,从而使其生长发育受到抑制。(4)各处理白兰花叶片的MDA含量呈现上升-下降-上升的趋势,说明白兰花对酸雨有一定的适应性,抗氧化系统也积极作出响应以抵御外界伤害,消除自由基,防止膜脂过氧化；但随着酸雨次数的增多,胁迫引起了白兰花叶片的膜脂过氧化加剧,对叶片细胞产生了伤害,且酸雨的酸度越强,伤害越严重。(5)酸雨胁迫使白兰花体内保护酶系统的活力和平衡受到破坏,活性氧积累,启动并加剧膜脂过氧化而造成整体膜的损伤；在多次酸雨胁迫下,保护酶系统所起的作用已经有限,不能再清除多余的自由基,白兰花受到伤害。(6)白兰花是一种对酸雨胁迫较为敏感的木兰科植物,会随着酸雨pH的减小和胁迫次数的增多而受到更大的伤害。更多还原

【Abstract】 Acid rain, one of the global environmental problems, is also major environmental issue of China. It has reported that acid rain gives rise to a large amount of economic losses and it does harm to the plants as well as ecological balance, Threaten from acid rain has become increasingly a cause for concern.In this study, Michelia alba.DC growing in a good condition and in the same age were planted in pots and treated by simulated acid rain under different pH values (pH= 2.0,3.0,4.0, 5.6). The morphological indices, the growth index and some physiological and biochemical indicators were determined to exploring the acid rain resistance mechanism of Michelia alba.DC. The work provides an experimental basis for acid rain theory on a certain plant species, and also it gives an important reference to the selection of urban green plants in acid rain control area. The experimental results are as follows:(1) Damage to Michelia alba. DC from acid rain is closely related to the acidity. The higher acidity and the higher occurrence frequency of acid rain, correspondingly, the heavier damage and the greater inhibition on Michelia alba. DC. The visible damage threshold of acid rain on Michelia alba. DC were pH= 3.0; the sensitivity of Michelia alba.DC to acid rain pollution are in gradeⅡunder pH= 2.0.(2) The new branch increment rate and the growth rate of Michelia alba. DC were decreased in accordance with the decreasing of pH values, The branch increment rates and growth rates in all treatment groups were unexceptionally different from the CK (p<0.05). The growth rate was a sensitive indicator to acid rain for Michelia alba. DC.(3) The stress of acid rain has an evident effect on the photosynthesis of Michelia alba. DC. The contents of chlorophyll, the contents of chlorophyll a/b, the net photosynthetic rates (Pn), the stomatal conductances (Gs), the intercellular CO2 concentrations (Ci), and the transpiration rates (WUE) were all decreased in accordance with the decreasing of rainfall acidity, indicating that the photosynthetic capacity of Michelia alba. DC is suppressed and the growth of Michelia alba. DC is inhibited.(4) The malondialdehyde (MDA) levels in the leaves of Michelia alba.DC under acid rain treatment showed up-down-up trends, implying that the orchids have some adaptability to acid rain. The antioxidant system make an active response to resisting outside hurts: eliminating free radicals, preventing peroxide of membrane lipid. With the increasement of the frequency of acid rain, the peroxidation of lipid in the leaves of Michelia alba.DC are aggravated, which injures the leave cells, the stronger the acidity of acid rain, the more serious injuries.(5) Acid rain stress also destroys the vitality and balance of endogenous protective enzyme system in Michelia alba. DC, the reactive oxygen species were accumulated, and the lipid peroxidation were enhanced as well as the bulk membrane was damaged. Under repeat acid rain stresses, the protective function of enzyme systems is heavily impaired, which can not remove excess free radicals, and it also can not prevent the Michelia alba. DC from outside hurts effectively.(6) The Michelia alba. DC is a Magnoliaceae species relatively sensitive to acid rain stress. The injury on Michelia alba. DC became heavier with the decreasing of pH values of acid rain and with the increasing of the stress frequency of acid rain.更多还原